Flexible package for hydrocolloid impression materials



Feb. 22, 1938. w. J. VAN ROSSEM FLEXIBLE PACKAGE FOR HYDROCOLLOIDIMPRESSION MATERIALS Filed June 5, 1936 AITTORNEYS.

Patented Feb. 22, 193% I UHTED STATES PATENT Fries FLEXIBLE PACKAGE FORHYDROCOLILOIID IMPRESSION MATERIALS Walter J. van Rossem,

- assignor to Surgiden West Los Angeles, Caliii.,, t, Ltd, WestHollywood,

. 2 Claims. This invention relates to a method of forming anadvantageous package construction in which a moisture-containingmaterial may be stored or marketed, and to the package construction thus5 formed, and pertains particularly to a package for a plasticmoisture-containing impression compound, comprising a container orenvelope of moisture-impervious coating material of high mechanicalstrength at ordinary temperatures i and marked flexibility attemperatures near the boiling point of water and a body ofmoisturecontaining hydrocolloid impression composition enclosed withinsaid container or envelope.

This application is a continuation-in-part of 35 my earlier applicationSerial No. 57,397, filed J anuary 3, 1936.

One of the important objects of the invention is to provide a packagewhich may be easily and inexpensively prepared and which will preserve90 a moisture-containing hydrocolloid composition without loss ofmoisture, for an indefinite period.

A further important object is to provide a package of the characterdescribed which com-- prises a moisture-impervious envelope structurecapable of elastic deformation at temperatures adjacent or in theneighborhood of the boiling point of water.

A further object of the invention is to provide a novel and advantageousmethodof forming a package for a moisture-containing hydrocolloid'composition.

The package of the present invention is primarily adapted for enclosingdental impression compositions having a reversible hydrocolloid 35 base.These compositions are in general semirigid when cool and must be heatedto render the same fluent for use. Compositions of this general type aredescribed in U. S. Patent No.

1,672,776 and in the two U. S. patents of Laurence 40 E. Harrison, Nos.2,021,058 and 2,020,311. Prior to the present invention thesecompositions have been marketed in the form of cylinders about one inchin diameter and 'four inches long wrapped in a tinfoil cartridge or thelike, or as described 45 in U. S. Patent No. 1,977,580, enclosed in acellulosic envelope which is in turn enclosed in a moisture-imperviousenvelope such as a glass bottle or a wax coating. One of the objectionsto the use of foil wrappers has been that, in ad- 50 dition to a slightloss of moisture, the composition became discolored due to contact withthe metal container, which prejudiced the user, and one of the principalobjections to the package described in Patent No. 1,977,580 is the costof the 55 double envelope'type of package as well as the danger ofrupture or fracture of the exterior envelope which permits loss ofmoisture from the composition through the cellulosic envelope. Accordingto the present invention a continuous moisture-impervious envelopecoating is provid- 5 ed for a body of such impression composition whichadequately protects the same from contamination and preserves themoisture content thereof, such envelope coating being of a materialwhich is of high mechanical strength at ordinary temperatures butreadily capable of elastic deformation at elevated temperatures wherebythe packages may be immersed in water and heated to render the containedcomposition fluent after which the package may be kneaded to homogenizethe composition and render the same suitable for use, without danger orrupture of the envelope during the kneading operation.

The coating material should be one which, even at the elevatedtemperatures at which the contained impression composition is handled torender the same fluent, retains a high degree of mechanical strength,and preferably also remains substantially moisture-impervious. Thecoating material is preferably one having a relatively high mechanicalstrength at ordinary temperatures, a melting point somewhat in excess of100 C. and relatively resilient and capable of elastic deformation attemperatures in the neighborhood of 100 C.- The ability of the materialto elastically deform at the high temperatures should persist to animportant degree during cooling from adjacent 100 C. to in theneighborhood of to C. as itis common practice in dental technique tocontinue the kneading of the heated 3.3 composition until thetemperature thereof has dropped to a point such that it may be insertedwithin the mouth of a patient without undue discomfort. Numerousmaterials are available,

, for the fabrication of this envelope, such as the -10 vinyl resins,among which may be listed the commercially available Koroseal (apolymerized vinyl halide) which has a melting point in the neighborhoodof 116 C. or combination solutions of cellulosic compounds and amoisturei5 proofing material such as rubber, resins, resinous gums, andhigh melting point waxes.

The continuous envelope for the above-described moistureecontaininghydrocolloid lmpression composition may be formed by any one of a numberof procedures. An advantageous procedure is that of forming an elongatedcylindrical or other suitably shaped body of the hy drocolloiocomposition by extrusion, molding or the like, and immersing the formedbody in a fluid bath of the material of which the envelope is to beformed, as by passing such body through said bath, so as to form acontinuous coating of the envelope material on the exposed surface ofthe hydrocolloid body, cutting the coated body into desirable lengthsand immersing the end portions of the cut lengths thereof in a fluidbath of coating material, as by dipping, and allowing the thuscompletely coated bodies to thoroughly dry. Alternatively, thehydrocolloid composition may be cut or otherwiseformed into bodies ofthe desired length and such bodies immersed, as by endwise dipping, intoa fluidbath of-the envelope material so as to form a coating on one endportion thereof, the coating on such end allowed to solidify, thebodyinverted and again immersed to a point somewhat above the end of thepreviously formed coat, so as to forma coating' over the other endportion overlapping the end of the first formed coat, and the coatingthen allowed to solidify and dry to form a continuous envelope over theentire surface of the body.

The accompanying drawing illustrates packages formed by the aboveprocedures and referring thereto:

Fig. 1 is a partly broken-away perspective view of a package formed bythe continuous coating procedure, before the coating material is placedover the end portions thereof;

Fig. 2 is a view corresponding to Fig. 1, showing a finished package,partly broken away longitudinally;

Fig. 3 is a broken-away perspective view of a body of impressioncomposition coated on one end by the double dipping procedure;

Fig. 4 is a view corresponding to Fig. 3, showing a complete packageformed by the double dipping procedure; and

Fig. 5 is a view corresponding'to Fig. 4, showing a package preparedfrom a preformed capsule or thimble sealed at one end by a dip coat.

Referring to the drawing, the form of pack age shown in Figs. 1 and 2may be formed by extruding a cylindrical body of the hydrocolloidcomposition into a fluid bath of coating ma-, terial, to form anexterior coating I. The hydrocolloid composition is then cut intosuitable lengths such as shown at 2 and the ends of the formed sticksare then dipped into a fluid bath of coating material to a sumcientdistance to form caps 3 at each end of the stick,, which overlap andintegrally bond with the end portions of the coating I, as shown at 3'.The exterior coating I may advantageously be formed by anodic depositionfrom a latex dispersion or the like, in which event the end caps 3 maybe formed from a'solution such as a composite celluloid-rubber solution,or from a solution of rubber.

The form of package shown in Figs. 3 and 4 may be produced by formingthe hydrocolloid composition into sticks 4 of suitable length, which aredipped endwise into a fluid bath of the coating material, to form anelongated cap.

5 at one end, and then dipped into said bath at the other end to asuflicient distance to form a cap 6 which overlaps and seals integrallywith the cap 5 intermediate the ends of the package, as at 1.

As shown in Fig. 5, a prefabricated capsule or thimble 8 may beemployed, into which the impression composition may be cast as at 9, andthe open end sealed by dipping into a fluid bath of coating compositionto a suflicient distance to form a cap portion l0 after the manner ofthe form illustrated in, Figs. 1 and 2.

In the fabrication of the form of package shown in Figs. 1 and 2, I mayemploy a mixture of celluloid and rubber in a suitable solvent, such asmay be formed from arr-intermixture of two equal volumes of cyclohexanolor cyclohexanol acetate in which from 10% to 30% by weight of celluloidand raw rubber have been respectively dissolved, the mixture beingpreferably evaporated to a thin honey-like consistency. Alternatively, Imay use a commercially available mixture containing the above-mentionedvinyl resin (Koroseal), such as that material marketed under the name ofKorolac which comprises a mixture of the polymerized vinyl halide and asuitable solvent which may be brought to a true solution by heating tosomewhat above 100 C.

Where the celluloid-rubber mixture is employed, it'will be necessary toallow the coating l to dry to some extent before the end-dipping ispractised, and in this connection it is preferable to cut the extrudedbodies into the short lengths 2 after the coating I has solidified orhardened to a sufiicient extent that the lengths may be handled withoutdamage to such coating. Immediately after cutting into the desiredlengths, the ends may be dipped to form the caps 3, and there will thusbe no significant loss in moisture from the composition during thepackage-forming operation. Alternatively, the extruded hydrocolloidcomposition may be passed through alternate hot air blasts and sprays ofthe coating composition, in a process of building up an adequate layerof moisture-impervious fllm coating, in which case the coated materialmay be handled in the end-dipping procedure promptly' after the coatingI is formed.

In the fabrication of the form shown in Figs. 3 and 4 I prefer to employa coating material which will solidify or gel at a rapid rate, so thatthe two' ends of the body of hydrocolloid composition may be coatedwithout the lapseof much time, so that the evaporation of moisture fromthe composition will be kept at a desirable minimum. For this type ofpackage, therefore, I prefer to employ a material of the nature of theabove-mentioned Korolac, which, being a solution of the resin Korosealonly at-a relatively high temperature, will gel out on contact with thehydrocolloid composition and form a continuous envelope over the dippedarea, which may be handled in the dipping of the other end substantiallyimmediately after the first end is dipped.

As a specific example of the practise of the invention in the formationof a moisture-impervious envelope of the resin -Koroseal", I heat a bodyof "Korolac containing approximately 10% Koroseal to a temperature ofapproximately 130 C., and dip one end of a preformed stick of thehydrocolloid composiiton into the fluid body, withdraw the stickpromptly, invert the same, and dip-the other end into the fluid body toa point overlapping the edge of the previous dipping, and then withdrawthe stick and allow it to dry.

The preformed stick of hydrocolloid composition will ordinarily be atordinary atmospheric temperature when dipped, and wili have a chillingeffect upon the fluid coating material in contact therewith, causingsuch material to be solidified or jelled on the surface of the stick.Due to the nature of the Korolac, this solidified condition is such thatthe stick may be immediately handled without damage to the coating,although the dipped package must be allowed to dry for several hoursbefore shipment, to allow the solvent to escape from the gel coating,and permit the coating to dry and form a thin, tough,moisture-impervious membrane.

brane from 0.005 to 0.009 thick. Where heavier coatings are desired,multiple dipping may be practised in such manner as to form a pluralityof material, in the production of membranes in excessof 0.01" inthickness.

Where a preformed capsule or envelope is employed, as in the form shownin Fig. 5, the capsule may be formed of any of the coating materialsabove mentioned, and the open end of the capsule may be sealed in thedescribed manner or, in the event that a, material such as Koroseal isemployed, the open end-may be causedto extend beyond the body ofcontained composition and heat-sealed as'by means of a hot iron or thelike.

Other methods of forming the package may be apparent to one skilled inthe art. For example, as described in my copending application, theenvelope may be formed by inserting a wire into a body of thehydrocolloid composition and dipping In. general, a single dip coat willbe adequate, forming a memsuperimposed thicknesses of coating 7 a bodyof moisture-containing hydrocolloid composition and an enclosingenvelope completely surrounding said body, said enclosing envelopecomprising a film of polymerized vinyl halide resin.

2. A moisture-impervious package comprising an elongated body ofmoisture-containing hydrocolloid composition, a film ofmoisture-impervious coating material enclosing one end of said body andextending along the length thereof toward the other end, a film ofmoisture-impervious coating material enclosing the other end of saidbody and overlapping and integrally sealed to said first-named film at aposition intermediate the length of said body, said moisture-imperviouscoating material comprising a polymerized vinyl halide resin.

WALTER J. VAN ROSSEM.

